BACKGROUND Erectile dysfunction (ED) is a common medical condition in middle-aged and elderly men; however, large-scale and multi-center epidemiologic studies about the treatment effects on ED in China are lacking. OBJECTIVE To elucidate the efficacy and safety of a phosphodiesterase type 5 inhibitor (PDE5-i) in the treatment of men with ED in China. METHODS Patients clinically diagnosed with ED from 53 andrology centers in 15 metropolitan areas in China who were willing to undergo treatment for ED were enrolled in the study. Each participant received 4 weeks of unique PDE5-i treatment, and completed the following forms (International Index of Erectile Function score 5 [IIEF-5], the Erection Hardness Score [EHS], Self-Esteem and Relationship [SEAR], and SF-36 of Health Related Quality of Life). Pre-and post-treatment data were compared using descriptive analysis. RESULTS A total of 1956 ED patients were included in this study; 1922 patients provided valid questionnaires for analysis. Four weeks of sildenafil treatment was considered effective and safe. Specifically, the IIEF-5 sores (11.30 ± 3.7 vs. 20.02 ± 5.1, P < 0.05), EHS levels (99.1% patients increases to level 3 or 4), and the SEAR scores (32.5 vs. 55.1, P < 0.05) were significantly improved compared to baseline. Sildenafil therapy also significantly improved the satisfaction, enjoyment, and frequency of sexual attempts and sexual activity, as well as physical vigor and mental health scores. CONCLUSION The present study provides direct evidence regarding the efficacy and safety of sildenafil therapy in a large sample of Chinese men with ED, thus verifying that sildenafil improved the symptoms and quality of sexual life.